Fix dynamic memoir image limits

api/services/memoir_images/settings.py

@@ -2,32 +2,52 @@ import os
 from dataclasses import dataclass
 
 DEFAULT_LIBLIB_TEMPLATE_UUID = "5d7e67009b344550bc1aa6ccbfa1d7f4"
+DEFAULT_MAX_IMAGES_PER_CHAPTER = 2
+DEFAULT_CHARS_PER_EXTRA_IMAGE = 1500
+DEFAULT_MAX_IMAGES_CAP = 8
+DEFAULT_IMAGE_PROVIDER = "liblib"
+DEFAULT_IMAGE_STYLE = "watercolor"
+DEFAULT_IMAGE_SIZE = "1280x720"
+DEFAULT_POLL_INTERVAL_SECONDS = 3
+DEFAULT_MAX_ATTEMPTS = 60
 
 
 @dataclass(frozen=True)
 class MemoirImageSettings:
-    enabled: bool
-    max_per_chapter: int
-    provider: str
-    default_style: str
-    default_size: str
-    poll_interval_seconds: int
-    max_attempts: int
-    liblib_template_uuid: str
+    enabled: bool = False
+    max_per_chapter: int = DEFAULT_MAX_IMAGES_PER_CHAPTER
+    chars_per_extra_image: int = DEFAULT_CHARS_PER_EXTRA_IMAGE
+    max_images_cap: int = DEFAULT_MAX_IMAGES_CAP
+    provider: str = DEFAULT_IMAGE_PROVIDER
+    default_style: str = DEFAULT_IMAGE_STYLE
+    default_size: str = DEFAULT_IMAGE_SIZE
+    poll_interval_seconds: int = DEFAULT_POLL_INTERVAL_SECONDS
+    max_attempts: int = DEFAULT_MAX_ATTEMPTS
+    liblib_template_uuid: str = DEFAULT_LIBLIB_TEMPLATE_UUID
 
     @classmethod
     def from_env(cls) -> "MemoirImageSettings":
         return cls(
             enabled=os.getenv("MEMOIR_IMAGE_ENABLED", "").lower() in {"1", "true", "yes"},
-            max_per_chapter=_get_int_env("MEMOIR_IMAGE_MAX_PER_CHAPTER", 2),
-            provider=os.getenv("MEMOIR_IMAGE_PROVIDER", "liblib"),
-            default_style=os.getenv("MEMOIR_IMAGE_STYLE_DEFAULT", "watercolor"),
-            default_size=os.getenv("MEMOIR_IMAGE_SIZE_DEFAULT", "1280x720"),
-            poll_interval_seconds=_get_int_env("MEMOIR_IMAGE_POLL_INTERVAL", 3),
-            max_attempts=_get_int_env("MEMOIR_IMAGE_MAX_ATTEMPTS", 60),
+            max_per_chapter=_get_int_env("MEMOIR_IMAGE_MAX_PER_CHAPTER", DEFAULT_MAX_IMAGES_PER_CHAPTER),
+            chars_per_extra_image=_get_int_env("MEMOIR_IMAGE_CHARS_PER_EXTRA", DEFAULT_CHARS_PER_EXTRA_IMAGE),
+            max_images_cap=_get_int_env("MEMOIR_IMAGE_MAX_CAP", DEFAULT_MAX_IMAGES_CAP),
+            provider=os.getenv("MEMOIR_IMAGE_PROVIDER", DEFAULT_IMAGE_PROVIDER),
+            default_style=os.getenv("MEMOIR_IMAGE_STYLE_DEFAULT", DEFAULT_IMAGE_STYLE),
+            default_size=os.getenv("MEMOIR_IMAGE_SIZE_DEFAULT", DEFAULT_IMAGE_SIZE),
+            poll_interval_seconds=_get_int_env("MEMOIR_IMAGE_POLL_INTERVAL", DEFAULT_POLL_INTERVAL_SECONDS),
+            max_attempts=_get_int_env("MEMOIR_IMAGE_MAX_ATTEMPTS", DEFAULT_MAX_ATTEMPTS),
             liblib_template_uuid=os.getenv("LIBLIB_TEMPLATE_UUID") or DEFAULT_LIBLIB_TEMPLATE_UUID,
         )
 
+    def effective_max_images(self, content_length: int) -> int:
+        """根据正文字数动态计算单章允许的最大图片数。"""
+        base_max = max(self.max_per_chapter, 0)
+        effective_cap = max(self.max_images_cap, base_max)
+        safe_length = max(content_length, 0)
+        extra = safe_length // self.chars_per_extra_image if self.chars_per_extra_image > 0 else 0
+        return min(base_max + extra, effective_cap)
+
 
 def _get_int_env(name: str, default: int) -> int:
     value = os.getenv(name, str(default))